Compressed air is the "fourth essential good" clean and accessible in the agri-food sector, after the three main ones: water, electricity and natural gas. The reliability of this fourth essential good depends on the predictability of the air pressure and the slightest leak can therefore be expensive.
According to the Compressed Air & Gas Handbook Seventh Edition,published by the Compressed Air & Gas Institute (CAGI), "A simple 6mm leak in a compressed air line can cost an installation from $2,500 to more than $8,000 per year. Locating and repairing leaks will result in significant savings, depending on pressure requirements and energy costs. »
Portable ultrasonic industrial imaging technology adds a visual component to traditional compressed air leak detection best practices to facilitate air leak detection and repair.
Here's a look at the air leaks commonly found in the food and beverage industry, as well as best practices and technologies to address them.
Compressed air applications in food and beverage plants
Food and beverage manufacturers must consider special considerations about compressed air leaks. Product consistency is critical to brand reputation and compliance, especially as factories and production equipment are subject to strict controls and regulations to avoid contamination.
In food and beverage plants, several air compressors are connected by pipes to carry compressed air to move products, operate pneumatic tools or pump liquids for various purposes in production lines, packaging and cleaning. Here are some examples:
Nitrogen snacks and air cushions: Nitrogen rinse is used to fill bags and create a cushion of air around fragile snacks and prevent them from being damaged. Oxygen is prohibited because it reacts with food products, especially those based on oil.
Food and cleanliness: Compressed air is purified and filtered to ensure food safety and maintain the adequate pressure dew point needed to prevent microbial growth.
Peeling fruits and vegetables: for their conditioning, pressurized air jets effectively remove the skins of fruits and vegetables. High-pressure compressed air is also used to cut food, a cleaner alternative to knives or blades.
Breweries, fermentation and bottling: Compressed air increases oxygen levels to complete the bacterial fermentation process. Air compressors reduce residual oxygen during bottling, and bottles are rinsed with carbon dioxide and filled with beer using pneumatic machines. Breweries operate in hot environments and, as a result, systems are more vulnerable to leaks.
Air leaks can, at any time, slow down production, affect product quality, cause safety or contamination issues, or all four at once, and compromise financial results.
The high and often hidden costs of air leaks
Compressed air and gases must be available at a specific pressure to meet production targets. Yet, many facilities believe that air leaks are part of the operating costs. These costs can be high: a leak that cannot be seen or heard costs $500 a year. Leaks that are easy to detect and hear can cost much more, as we have indicated.
Several factors associated with air leaks affect profitability:
Loss of efficiency: Compressed air systems that are not regularly maintained after installation can lose 20-30% of compressed air through leaks alone.
Additional costs: Pressure drop is often misdiagnosed as equipment failure, resulting in additional investments in new air compressors.
Downtime: Lost production time due to pressure drops or the installation of new equipment will require downtime and will have a negative impact on the schedule. Unplanned downtime costs an average of $200 per minute, which is why it's important to avoid it.
Product quality: Insufficient pressure results in a sealing defect in the packaging or an edible product that does not meet texture or flavor requirements.
Product safety: Leaks that cause contamination result in high costs in terms of waste, compliance penalties and reputational damage.
Environmental impacts: Systems with leaking air and gas become inefficient, which impacts the company's carbon footprint and prevents it from achieving its sustainability or environmental goals.
The formula used to determine the magnitude of compressed air leakage in a facility is as follows: Leakage (%) = (T x 100) ÷ (T + t) T = charging time (minutes), t = unloading time (minutes).
If the compressed air system is configured with on/off controls, start your air compressor when there is no demand from the system (after working hours or outside of shiftwork). Then perform several compressor cycle readings to determine the average system unloading time.
Traditional methods and technology to repair air leaks
The first step in processing and cost control is to detect air leaks at their point of origin. Here is a list of common leakage points:
FRL (filter/regulator/lubricant combinations)
Pneumatic storage tanks
Threaded fittings for pipes
Air leaks are a major problem because they are legion and difficult to find. Once found and repaired, other leaks tend to appear due to normal wear and tear of the system.
Although it is not possible to eliminate every leak, their total number can be reduced by targeted inspection using traditional detection methods. As part of these methods, when a leak is located, a paper label is used to mark the place. Here are four traditional detection methods:
A whistle indicates the presence of leaks; the leak is therefore important, because only a sound level above 60 dBA is audible without leak detection equipment. Since most factories are noisy and workers often have to wear hearing protection, listening for leaks must be done during downtime: between workstations, on weekends or during scheduled maintenance.
Water and soap
Technicians spray soapy water on areas where leaks are audible and bubbles appear on the leakage point. This method is laborious, far from precise, and requires cleaning, because the splashes of soapy water are a risk of slipping. In some clean processes protected against contamination, it is not allowed.
Ultrasonic acoustic detection
During downtime, technicians with headphones look for potential leakage points using a dish-shaped or cone-shaped accessory. When a leak noise is detected, the technician uses a wand-shaped device that he must hold a few centimeters from the leak to locate the exact location.
Calling on independent experts
Engineers or other experts are usually hired once a year to save money and avoid disruption. They use one or more traditional techniques, and consult the repairs and controls carried out by the internal technicians.
None of these methods are foolproof and most require downtime, resulting in wasted time and money.
Pilot test helps roaster easily identify 10% energy savings
Project engineers from a coffee roasting company participated in a pilot study using ultrasonic imaging technology in a facility where conditions tend to generate many leaks. The test revealed that the company could save more than 10% per year on its energy consumption thanks to the new leak detection device.
The 27,871-square-metre facility houses a coffee roasting and packaging area, a coffee wet processing area and a tea blending and packaging area. All operations require adequate air pressure to carry out processes and traditional leak detection methods are no longer suitable.
On average, the facility uses 28,000 to 45,000 cubic meters per minute of compressed air. The company's compressed air system, which includes five air compressors with a total output of 585 horsepower, powers the automation and pipes used to power the site's nitrogen production system. Nitrogen is used to obtain better quality coffee. In addition, the inert gas is used for tea mixing.
Using the ultrasonic imaging device, the team found potential energy savings of 10%, which is in line with their goal of improving sustainability. The new approach also showed how the team could simplify the air leak detection process, allowing project engineers to let staff work on products rather than having to stop for long periods of time in order to detect and repair air leaks.
In a pilot test, a roaster used an ultrasonic camera to easily identify and mark up to 52 air leaks, including leaks in hard-to-reach locations.
Visualization of air leakage with portable ultrasonic imaging technology
An advance in leak detection technology, in the form of a portable ultrasonic acoustic camera, facilitates leak detection and avoids lost profits.
The ultrasonic camera presented by Fluke Corporation allows users to locate and view air leaks on an LED screen in real time through a sight-trip process that does not require a specialized technician. Most users can master this technology in about ten minutes. Technicians can also work quickly from a safe distance while the equipment is running. In addition, the device makes it easier to find leaks in hard-to-reach places or to distinguish between several leaks in the same area.
The portable ultrasonic acoustic camera is equipped with a set of ultra-sensitive microphones that detect sounds in the human hearing and ultrasound ranges and then present them visually. The device then applies proprietary algorithms to the results and instantly produces a visual map of the leak on the screen. The leak image is overlaid with an image of the visible light area, allowing operators to quickly locate the location of the leak.
Fluke ultrasonic acoustic camera analyzes areas up to 50 meters under normal industrial conditions.
The ultrasonic camera can also be used to monitor the proper execution of repairs. If you have any questions, analyses captured as photos or live videos can be shared and reviewed with colleagues. Thanks to the captured images, there is no longer any need to climb a ladder or mark leaks with traditional fragile physical labels.
Best Practices for Reducing Compressed Air Leakage
Whether using conventional or new detection methods, now is the time to eliminate hidden costs and waste due to air leaks. Here are some best practices to follow:
Take a holistic approach
Often, repairing a leak increases the pressure on the system. Small leaks then become larger and affect the entire system. Combine changes with comprehensive strategies for better energy utilization and more robust control systems. Although they can be difficult to achieve, capital investments often result in energy savings that significantly reduce payback time.
Frequent audits, not limited to the usual annual or quarterly leak inspections, save time, money and resources in the long run, even if you need to shut down the equipment. Thanks to new imaging technologies, you can focus on leaks and permanently repair them without wasting valuable production time.
Confirm the root causes of pressure drops
A pressure drop can be misdiagnosed as equipment failure. Before incurring capital expenditures, the control and repair of leaks can save thousands or even hundreds of thousands of euros and instantly regain its production capacity.
Record, track and verify over time
It is important to note the exact places where leaks have occurred, as these weak points are often the ones where new leaks occur, and then inspect these areas regularly. Recording information online makes it easy to share data and use it to discipline the control process. Check shortly after the repair to determine if the leaks have been eliminated or if they require additional attention.
(*) Javier Irazola, Global Product Manager for the Industrial Imaging Group at Fluke Corporation, recently led the commercialization of acoustic imaging solutions. With eight years of engineering and project management experience with energy and water suppliers in the U.S. and Europe, he then also worked for three years in the Product Innovation department of Fluke Industrial Group.
All photos are reproduced with the kind permission of Fluke Corporation.
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